Method and system for emptying wetlines of a tanker truck

ABSTRACT

In a system and method for emptying wetlines on a tanker truck, a pipe is secured to the tanker truck and extends from the wetlines to the top of the housing tank of the tanker truck. A pump is mounted in the pipe or a housing connected to the pipe. The pump is preferably driven by air flow from a compressor.

FIELD OF THE INVENTION

[0001] The invention relates to emptying wetlines of tanker trucks priorto the trucks embarking on a journey to deliver fuel to gas stations.

BACKGROUND OF THE INVENTION

[0002] The filling and emptying of tanker trucks is achieved through asystem of pipes known as wetlines. Tanker trucks typically have one ormore housing tanks for housing different grade fuels. In the pastgasoline was filled into these housing tanks by pouring the liquid infrom the top. However, due to the hazard of having someone climb on topof the truck to supervise the filling, as well as the substantial vaporemissions that took place in such a system, regulations subsequentlyrequired the filling from below.

[0003] While this solved some of the problems, it introduced a newhazard. The wetlines which provided the interconnecting pipe sectionsbetween the housing tanks and the supply hoses, remained full of liquidonce the filling process was complete. At about a gallon per foot ofpipe, a tanker truck with 3 sets of wetlines for its three housing tankscould end up carrying 20 to 45 gallons of fuel in its wet lines. Asillustrated in FIG. 1, these wetlines are positioned below the tankertruck where they are vulnerable to breach during a motor vehicleaccident. Cars colliding with the tanker truck often end up breaking thewetlines and coming to rest under the tanker truck. The fuel in thewetlines typically spills onto the colliding car and ignites, resultingin severe human injuries and even death.

[0004] Various approaches have been proposed to address this problem.One solution is to drain the fluid from the wetlines after filling. Theproblem with this approach is one of weights and measures. Since thetanker truck is effectively considered as having received the 20-30gallons in the wetlines, draining this fuel back into the supply tankproduces accounting headaches and requires that the fuel that issiphoned off be measured and credit given accordingly. This is both acomplex and costly undertaking.

[0005] Another approach is to provide a protective cage around thewetlines. This, however is economically unattractive since it addssignificant weight to the tanker truck, which translates into lower fuelcarrying capacity.

[0006] Yet another approach is to force a gas into the wetlines, therebyforcing the liquid remaining in the wetlines after the filling process,into the housing tank of the tanker truck. This, however, requirestremendous pressure to be generated in order to force the fuel upagainst the downward force of the fuel in the housing tank. As a result,powerful pumps or other mechanisms have to be made available, greatlyadding to the cost of filling tanker trucks and conveying fuel. Also, itrequires the use of an inert gas or other gas that does not cause anexplosion hazzard.

SUMMARY OF THE INVENTION

[0007] The present invention discloses a method and system for emptyingthe wetlines of tanker trucks, so as to avoid the problems in the priorart solutions. The invention involves the use of a separate pipe forconveying fuel from the wetlines to the top of the housing tank of thetanker truck. It further involves the use of a pump that is driven byfluid flow. Preferably the pump is a diaphragm pump which is preferablydriven by compressed air flow from a conventional compressed air source.

[0008] The present invention also discloses a system and methodgenerally for propelling liquid in a pipe, making use of a pump drivenby regular compressed air, wherein the compressed air does not havedirect contact with the liquid.

[0009] According to the invention, there is provided a method ofemptying wetlines associated with a housing tank of a tanker truck,comprising, pumping liquid in the wetlines into the housing tank,through a separated pipe extending from the wetlines to a location at ornear the top of the housing tank. Typically, separate pipe extends fromthe wetlines to a location above or near the highest surface of theliquid in the housing tank. Preferably, the separate pipe extends alongan inner surface of the housing tank, but it can also extend along anouter surface of the housing tank. Typically, the liquid is pumped usinga diaphragm pump mounted in the pipe or in a housing connected in fluidflow communication with the pipe.

[0010] Further, according to the invention, there is provided a meansfor emptying wetlines associated with a holding tank on a tanker truck,comprising, a pipe extending from the wetlines to a location at or nearthe top of the housing tank, and a pump for pumping the liquid along thepipe into the housing tank. Preferably the pump is a diaphragm pumpmounted in the pipe or in a housing connected in fluid flowcommunication with the pipe. The pump is preferably operated by fluidflow such as the flow of air, water, or oil, for example. Preferably airflow is used, making use of a conventional compressed air source.

[0011] Still further, according to the invention, there is provided ameans for propelling liquid through a pipe, comprising a diaphragm pumpwhich is operated by the flow or regular air from a conventionalcompressed air source.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a side view of a tanker truck showing a set of wetlines;

[0013]FIG. 2 is a sectional end view of the tanker truck of FIG. 1;

[0014]FIG. 3 is a sectional end view of one embodiment of a wetlineemptying system of the invention, and

[0015]FIG. 4 is a sectional end view of another embodiment of a wetlineemptying system of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0016] A typical tanker truck is shown in FIGS. 1 and 2. Tanker trucks100 typically include one or more housing tanks 102, each housing tanksupporting a particular grade fuel, and having its own set of wetlines104. The wet lines 104 each include a filling pipe 106 and a drainingpipe 108. Fuel is supplied to a filling pipe 106 at a supply station bymeans of a supply hose 110 connected between a supply tank and a dryconnector 112 on the filling pipe 106. The dry connector 112 provides aliquid tight connection for the supply hose 110 and includes a valvethat is automatically pushed open by a pin (not shown) mounted in themating portion 114 on the supply hose 110.

[0017] A second valve 120 is located between the housing tank 102 andthe wet lines 104. This valve 120 is a one way valve that is pressureoperated and automatically opens as fuel flows into the filling pipe106.

[0018] Emptying of a housing tank 102 is achieved by draining the fuel,under gravity, from the draining pipe 108. As with the filling pipe 106,the draining pipe 108 is terminated by a dry connector 122.

[0019] Once fuel has been supplied to a housing tank 102 via the fillingpipe 106, the supply hose 110 is disconnected, thereby, automaticallyclosing the valve 120 and the valve of the dry connector 112. It will beappreciated that fuel remains trapped in the wet line 104. Since each ofthe housing tanks 102 has its own set of wetlines 104, and each retainsseveral gallons of fuel, the combined volume of fuel in the wetlines 104of a typical tanker 100, presents a significant danger.

[0020] In accordance with the present invention, the fuel in thewetlines 104 is pumped out of the wetlines 104 and into the housingtanks 102. As shown in FIG. 3, each of the wetlines 104 is provided witha pipe 130 that extends from the lowest point in the wetline 104 to alocation near the top of the housing tank. In a preferred embodiment,the pipe 130 runs along a surface (in this case, the outer surface) ofthe wetlines 104, passes through the wall 132 of the housing tank 102 ata location 134 adjacent to the valve 120, and runs up the inner surfaceof the housing tank 102 to a location near the top of the housing tank.Thus fuel is fed from the wetlines 104 into the housing tank 102,thereby emptying the wetline 104. By having the pipe 130 empty out nearthe top of the housing tank 102, in this embodiment, above the highestsurface of the fuel in the housing tank, there is no need to force thefuel up into the tank against the weight of the fuel in the tank, as inthe prior art system. It will be appreciated that the outlet of the pipe130 could also be located below the surface of the fuel in the housingtank 102, however, the outlet should ideally not be located too farbelow the upper surface of the fuel in the housing tank, to minimize thepressure at the outlet. It will also be appreciated that the pipe 130could, instead, be mounted on an outer surface of the housing tank 102.In tanker trucks having a double walled housing, the pipe 130 could runbetween the two walls. While the term pipe has been used to depict thefuel path 130, this could be either a rigid pipe or a flexible hose.

[0021] The invention contemplates any pump system connected to the pipe130. In one embodiment a centrifugal pump is used, and in anotherembodiment a diaphragm pump 200 is used. The pump 200 is mounted in ahousing 202 which is in fluid communication with the pipe 130. In oneembodiment, the pump 200 was made of a non-ferrous metal, in this casebrass, and having a housing 202 with a male screw connector receivablein a complementary female screw connector welded to the wetline 104. Inthe embodiment of FIG. 3, a pump 200 is connected directly to thewetlines, with one pump being provided for each set of wetlines. Thepipes 130 extend from the pumps to the top of the housing tanks.

[0022] It will, however, be appreciated that in another embodiment, asshown in FIG. 4, a single pump 240 could be provided to pump fuelsequentially for each of the wetlines on a tanker truck. In such anarrangement each of the pipes 130 would be in two sections with onesection (section 250) extending from the wetline to the pump and asecond portion (section 252) extending from the pump to a housing tank.This is discussed further below, with respect to FIG. 4.

[0023] In the FIG. 3 embodiment, the pump 200 is driven by the flow ofregular air from a conventional compressed air source 210 connectedthrough a hose 212 to the pump 200. The compressed air source 210 can beany conventional compressor as is commonly used to inflate tires orpower tools. The invention preferably envisages the use conventional aircompressors which are readily available and thus allow quick and cheapimplementation of the invention. By keeping the air supply driving thepump, separate from the fuel, and avoiding contact between the airsupply and the fuel, this invention realizes the benefit of using acheap, readily available propulsion source for the pump, while avoidingthe need for inert gases or other gases that reduce the risk ofexplosions.

[0024] It will be appreciated that the pump 200 could, instead, bedriven by a motor such as an electric motor connected, however, such anarrangement is less desirable when flammable fluids are to be pumped,due to the danger of sparks and the possibility of a fire or explosion.It will be appreciated that, if the pipe 130 is wide enough toaccommodate the pump 200, the pump could be mounted directly in the pipe130. It will also be appreciated that either the pipe 130, or housing202, or the wetlines 104 will have to be provided with a valve forallowing air to enter the system as the fuel is sucked out of thewetlines 104.

[0025] Furthermore, in order to ensure that substantially all of thefuel in the wetlines 104 is removed, the housing 202 is preferablymounted at the lowest point on the wetlines 104. This may require theshape or attitude of the wetlines 104 to be adjusted. In the embodimentof FIG. 3, the housing 202 is mounted at an elbow 222 of the wetlines104, wherein the wetlines 104 are shaped to define the elbow 222 as thelowest point on the wetlines 104.

[0026] Instead, as shown in the FIG. 4 embodiment, the section 250 ofthe pipe 130 could feed into the wetlines 104 and extend to a low pointof the wetlines 104. This allows the pump 240 to be mounted anywhere onthe truck, with the various sections 250 extending to the pump 240, andthe sections 252 extending from the pump to the tops of the housingtanks 254. It will be appreciated that in this embodiment, valves areincluded in the pipe sections 250 to ensure that the pump 240 pumps fromone set of wetlines 104 only at any one time. The valves can be manuallycontrolled or by an electronic controller that sequentially opens andcloses the valves in the sections 250 to sequentially drain the wetlines104.

[0027] The embodiments of FIGS. 3 and 4 use compressed air as apropulsion source for the pump 200, since compressed air is readilyavailable. However, other fluid flow could, instead, be used to drivethe pump 200, such as water or oil flowing through the pump 200.

[0028] While the invention was described specifically for propellingfuel from wetlines of a tanker truck into the housing tank of the truck.However the use of an air driven pump which is driven by regular airfrom a conventional compressed air source, where the air is keptseparate from the liquid being pumped, has other applications. Theinvention can be used for conveying liquid along a pipe generally, in acost effective manner without resorting to an unconventional compressedair sources such as compressed inert gas, and without causing a safetyhazzard.

[0029] Thus, while the invention was described in detail with respect toa specific implementation, it has much broader scope, as defined by theclaims to this application.

What is claimed, is:
 1. A method of emptying wetlines associated with ahousing tank of a tanker truck, comprising, pumping liquid in thewetlines into the housing tank, through a separate pipe extending fromthe wetlines to a location at or near the top of the housing tank.
 2. Amethod of claim 1, wherein the separate pipe extends from the wetlinesto a location above or near the highest surface of the liquid in thehousing tank.
 3. A method of claim 1, wherein the separate pipe extendsalong an inner surface of the housing tank.
 4. A method of claim 1,wherein the separate pipe extends along an outer surface of the housingtank.
 5. A method of claim 1, wherein the liquid is pumped using adiaphragm pump.
 6. A method of claim 5, wherein the pump is driven byfluid flow.
 7. A method of claim 6, wherein the fluid flow is air flowfrom a conventional compressed air source of regular air.
 8. Means foremptying wetlines associated with a holding tank on a tanker truck,comprising a pipe extending from the wetlines to a location at or nearthe top of the housing tank, and a pump for pumping the liquid along thepipe into the housing tank.
 9. Means according to claim 8, wherein thepump is a diaphragm pump mounted in the pipe or in a housing connectedin fluid flow communication with the pipe.
 10. Means according to claim8, wherein the pump is a diaphragm pump driven by fluid flow.
 11. Meansaccording to claim 10, wherein the fluid flow is regular air flow from aconventional compressed air source.
 12. Means according to claim 10,wherein the fluid is air, water, or oil.
 13. Means according to claim 8,wherein the pipe extends from the wetlines to a location above or nearthe highest surface of the liquid in the housing tank..
 14. Meansaccording to claim 8, wherein the pipe extends along an inner surface ofthe housing tank.
 15. Means according to claim 8, wherein the separatepipe extends along an outer surface of the housing tank.
 16. Means forpropelling liquid through a pipe, comprising a diaphragm pump mounted inthe pipe or a housing connected in fluid flow communication with thepipe, wherein the pump is operated by air flow from a conventionalcompressed air source.